A lower affinity to cytosolic proteins reveals VDAC3 isoform-specific role in mitochondrial biology

María Queralt-Martín (1) , María Queralt-Martín (2) , Oscar Teijido (1) , Nabill Munshi (2) , Daniel Jacobs (1) , Adam J Kuszak (3) , Olga Protchenko (3) , Simona Reina (4) , Andrea Magrì (4) , Vito de Pinto (4) , Sergey M Bezrukov (1) , Jeff Abramson (2) , Tatiana K Rostovtseva (1)

1 NICHD - Eunice Kennedy Shriver National Institute of Child Health and Human Development
2 UCLA - University of California [Los Angeles]
3 National Institute of Diabetes and Digestive and Kidney Diseases [Bethesda]
4 Unict - Università degli studi di Catania = University of Catania

Voltage-dependent anion channel (VDAC) is the major pathway for the transport of ions and metabolites across the mitochondrial outer membrane. Among the three known mammalian VDAC isoforms, VDAC3 is the least characterized, but unique functional roles have been proposed in cellular and animal models. Yet, a high-sequence similarity between VDAC1 and VDAC3 is indicative of a similar pore-forming structure. Here, we conclusively show that VDAC3 forms stable, highly conductive voltage-gated channels that, much like VDAC1, are weakly anion selective and facilitate metabolite exchange, but exhibit unique properties when interacting with the cytosolic proteins α-synuclein and tubulin. These two proteins are known to be potent regulators of VDAC1 and induce similar characteristic blockages (on the millisecond time scale) of VDAC3, but with 10-to 100-fold reduced on-rates and altered α-synuclein blocking times, indicative of an isoform-specific function. Through cysteine scanning mutagenesis, we found that VDAC3's cysteine residues regulate its interaction with α-synuclein, demonstrating VDAC3-unique functional properties and further highlighting a general molecular mechanism for VDAC isoform-specific regulation of mitochondrial bioenergetics.

Domaines: Biophysique

María Queralt-Martín, María Queralt-Martín, Oscar Teijido, Nabill Munshi, Daniel Jacobs, et al.. A lower affinity to cytosolic proteins reveals VDAC3 isoform-specific role in mitochondrial biology. Journal of General Physiology, 2020, 152, ⟨10.1085/jgp.201912501⟩. ⟨hal-03445737⟩